assessment of microleakage of class v composite resin restoration following erbium-doped yttrium aluminum garnet (er:yag) laser conditioning and acid etching with two different bonding systems

introduction: the use of laser for cavity preparation or conditioning of dentin and enamel surfaces as an alternative for dental tissue acid-etch have increased in recent years. the aim of this in vitro study was to compare microleakage at enamel-composite and dentincomposite interfaces following erbium-doped yttrium aluminum garnet(er:yag) laser conditioning or acid-etching of enamel and dentin, hybridized with different bonding systems. methods: class v cavities were prepared on the lingual and buccal surfaces of 50 recently extracted intact human posterior teeth with occlusal margin in the enamel and gingival margin in the dentin. the cavities were randomly assigned to five groups: group1:conditioned with laser (energy=120mj, frequency=10hz, pulse duration=100μs for enamel and energy=80mj, frequency=10hz, pulse duration=100μs for dentin) + optibond fl, group2:conditioned with laser + etching with 35% phosphoric acid + optibond fl, group3:conditioned with laser + clearfil se bond, group 4 (control):acid etched with 35% phosphoric acid + optibond fl, group 5 (control): clearfil se bond. all cavities were restored using point 4 composite resin. all samples were stored in distilled water at 37°c for 24 h, then were thermocycled for 500 cycles and immersed in 50% silver nitrate solution for 24 h. the teeth were sectioned bucco-lingually to evaluate the dye penetration. kruskal-wallis & mann-whitney tests were used for statistical analysis. results: in occlusal margins, the least microleakage showed in groups 2, 4 and 5. the maximum microleakage was observed in group 3 ( p =0.009). in gingival margins, the least microleakage was recorded in group2, while the most microleakage was found in group 5 ( p =0.001). differences between 5 study groups were statistically significant ( p <0.05). the microleakage scores were higher at the gingival margins. conclusion: the use of the er:yag laser for conditioning with different dentin adhesive systems influenced the marginal sealing of composite resin restorations.